(1) Field of the Invention
The present invention relates to the field of seats for aircraft, in particular rotorcraft, arranged to provide safety for the passengers installed on the seats in the event sudden deceleration of the aircraft and/or in the event of a crash.
The present invention relates more particularly to the structural organization of a bench for aircraft enabling a variable number of passengers to be received under the safety conditions specifically required of aircraft transporting passengers.
(2) Description of Related Art
Seats for aircraft have means for protecting passengers installed on the seats in the event of the aircraft being subjected to strong deceleration and/or in the event of a crash. For this purpose, aircraft seats are commonly fitted with provisions as set out below.
Firstly, an aircraft seat is commonly fitted with a harness for individually holding a passenger in a seated position on the seat. The harness comprises a set of straps, preferably four straps, including at least two shoulder straps and two lap straps. Each strap is anchored to the seat at one end, possibly via a winder and/or means for adjusting the length of the strap, and each is typically provided with an attachment member at its other end.
The attachment members fitted to the straps commonly co-operate with respective locking members incorporated in a buckle of the harness in a position in which the harness is looped around the passenger to hold the passenger in the seated position on the seat.
The buckle conventionally comprises an actuator operable by the passenger in order to release at least some of the attachment members from the engagement exerted thereon by the locking members, thus enabling the harness looped around the passenger to be opened so that the passenger can leave the seat.
Concerning the organization of such harnesses fitted to aircraft seats, reference may be made for example to the Document FR 2 851 974 (EADS Sogerma Services), which describes such a harness.
Secondly, aircraft seats are organized to avoid, or at least limit, deformation under the effect of deformation of a floor of the aircraft on which the seat is fastened. Such deformation of the floor is caused in particular in the event of an aircraft crashing. For this purpose, aircraft seat architecture is organized so that, in the event of a crash, it accompanies and/or compensates deformation of the floor on which the seats are installed on board the aircraft. Such provisions serve to protect passengers by limiting the impact of deformation of the floor on a seat bucket receiving one or more passengers.
Thirdly, an aircraft seat is provided with one or more energy absorbers suitable for absorbing the energy resulting from the forces to which said bucket is generally subjected in the event of strong deceleration of the aircraft. Such energy absorbers are constituted in particular by deformable means having a predetermined force threshold.
More particularly, a common utilization situation of an aircraft seat should be taken into consideration in which the passengers installed on the seat are not subjected to the effects of strong deceleration of the aircraft. In such a situation, the energy absorbers support without deforming at least the seat pan of the seat and possibly the entire bucket of the seat.
In a critical utilization situation of the seat, the passenger(s) installed on the seat is/are subjected to strong deceleration of the aircraft. Under the effect of the load to which the bucket supporting the weight of the passenger(s) is subjected, the energy absorbers deform on being subjected to a force higher than said force threshold. A change in the dimensions of the deformable means of the energy absorbers, which may equally well be in compression or in elongation, enables at least the seat pan and possibly the entire bucket (pan and back) to move in order to protect the passenger(s) being subjected to the strong deceleration of the aircraft. At the end of the deformation stroke of the energy absorbers, the bucket is retained by the energy absorbers, at least via the seat pan.
By way of example, reference may be made on this topic to the following Documents FR 2 683 191 (Israel Aircraft Ind. Ltd.), DE 4 312 343 (Eurocopter Deutschland), FR 2 950 607 (Eurocopter France), U.S. Pat. No. 5,125,598 (R. G. Fox), and US 2010/0270836 (G. A. Mowry et al.), which documents describe such energy absorbers using deformable means that are activated at a predetermined force threshold to which the bucket is subjected in the event of strong deceleration.
Among aircraft seats, single-occupant seats are known, such as those used by pilots, for example, and benches are also known for receiving a plurality of passengers.
Benches are naturally provided with a plurality of harnesses, the number of harnesses matching the number of passengers as determined by the optimum passenger-receiving capacity of the bench. The respective locations where harnesses are installed on the bench and/or the number of said harness buckles for looping a harness around a passenger conventionally determine the number and the locations identifying the places on the bench that can receive respective passengers.
An aircraft bench commonly has a carrier structure supporting a frame. The frame provides at least one said bucket made up of a seat pan and of a seat back for receiving one or more passengers. The frame may provide a plurality of individual passenger buckets or a collective bucket suitable for receiving a plurality of passengers jointly.
The carrier structure conventionally has a stand typically provided with catches for fastening to a floor of the aircraft, in particular by means of bolts or by co-operation between said catches and rails incorporated in the floor of the aircraft. The stand carries the frame via structural elements of the carrier structure connecting stand members together, such as structural elements made up of uprights and/or of spars.
The energy absorber(s) is/are potentially incorporated in the carrier structure, e.g. being interposed between the stand and said structural element. Reference may be made for example on this topic to the following Documents: EP 0 423 348 (Kiguchi Shigeru et al.) and U.S. Pat. No. 5,657,950 (Ind Technology Research Int. et al.).
Also by way of example, the energy absorber(s) is/are potentially interposed between the carrier structure and the frame. By way of example, reference may be made on this topic to the following Documents EP 0 716 980 (Eurocopter France), U.S. Pat. No. 5,125,598 (R. G. Fox), and US 2010/0270836 (G. A. Mowry et al.).
Concerning the Document US 2010/0270836 (G. A. Mowry et al.), the energy absorber is more particularly formed by a spring carried by the seat pan and placed under stress by means of a wire. The wire engages the spring at one of its ends and the frame at its other end via a pulley around which the wire is wound.
An advantage of benches is that they enable a plurality of passengers to be received while presenting weight and overall size that are small compared with a plurality of seats for individually receiving the same number of passengers. Nevertheless, optimizing the number of passengers who can be received on a bench of the smallest possible size implies restricting the amount of space available on the bench for each of the passengers, to the detriment of their individual comfort.
In this context, it is found that the bench may be occupied by some number of passengers that is smaller than its optimum passenger-receiving capacity. Nevertheless, the locations of the bench reserved for each of the passengers are predetermined by the arrangement of the bench, in the context of constraints associated with making safe the passengers installed on the bench in the event of strong deceleration and/or in the event of the aircraft crashing.
Under such conditions, improving the individual comfort of some number of passengers smaller than the total passenger-receiving capacity of the bench is limited and deserves improving. It should be observed that such an improvement needs to take account of the constant search for lightening a bench in order to reduce its weight as much as possible, which is important in aviation, and also, as mentioned above, needs to take account of making passengers safe when faced with strong deceleration of the aircraft and/or in the event of a crash.
In the general field of transporting passengers on board vehicles, proposals have been made for benches that seek to be light in weight, and possibly also adaptable, so as to be able to receive varying numbers of passengers.
By way of example, according to U.S. Pat. No. 7,594,701 (Conax Florida Corporation), an aircraft bench may comprise a carrier structure provided with means for fastening it both to the floor and to a wall of the aircraft.
According to that U.S. Pat. No. 7,594,701, the carrier structure is covered in a fabric providing an overall seat pan for receiving a plurality of passengers, said fabric being supported by a mesh of straps suitable for being tensioned to a greater or lesser extent on the carrier structure.
Also by way of example, according to Document EP 2 069 164 (Indiana Mills & Mfg.), a vehicle bench provided with safety belts can receive varying numbers of passengers by moving buckles for locking said belts in the looped position along a rail that is installed on the seat.
Still with reference to the comfort of the users of seats, the traditional seat pan of such a seat is a single piece that receives the buttocks of all of the users. It has nevertheless been found that the comfort of users can be improved by subdividing the seat pan of a seat into pairs of individual seat pan members respectively receiving one or the other of a user's buttocks.
Reference may be made on this topic to the seats described by the following Documents: EP 2 200 481 (Massachusetts Inst. Technology), and U.S. Pat. No. 2,799,323 (Berg Joseph), for example.
According to Documents EP 2 200 481 and U.S. Pat. No. 2,799,323, the individual seat pans of a seat are themselves individually movable in order to adapt their orientations as a function of the posture of the user installed on the seat, such that the muscle tensions suffered by the user are limited.
Other documents have been considered, and in particular the specification “Airworthiness standards: Normal category rotorcraft”, 14CFR27.562, Title 14, Parts 27.29 (2002), and the following Documents EP 0 433 388, US 2008/211219, US 2009/267390, and US 2013/228652.